Juglans nigra (Black Walnut)

Michael's Opinion

This may be considered a problem tree in the landscape because of the toxis substance Juglone that it produces. It can however, be quite a striking specimen in maturity. It can be long lived and develops a strong silhouette in the winter garden. It can be messy at times when in fruit and should not be planted around patios or paths as the golf ball size fruit are quite hard and they can stain concrete.

Botanical Information

FamilyJuglandaceae
GenusJuglans
Speciesnigra
CategoryWoody
TypeTree (deciduous)
Pronunciation

Details

USDA Hardiness Zone6b - 7a
USDA Hardiness Ref.
Canadian Hardiness Zone6
Canada Hardiness Ref.
RHS Hardiness ZoneH6
RHS Hardiness Ref.
Temperature (°C)-21 - (-15)
Temperature (°F)-5 - 5
Height35 m
Spread 5 m
GrowthSlow

Description and Growing Information

General DescriptionJuglans nigra or Black Walnut is a very common tree in southern Ontario, Canada and easily grown from harvested nuts. It is not widely available in the trade.
ID CharacteristicLarge, green-husked fruit that releases a soapy scent.
ShapeRounded crown.
LandscapeHas limited use since it emits a substance called juglone that has fungicidal and antibiotic properties and retards the growth of many plants. However, there are many plants that can tolerate juglone. It is a stately, long-lived specimen and can, as in the Cuddy Gardens in Strathroy, provide an anchor to the landscape. The tree is quite messy when in fruit.
CultivationAn easy tree to cultivate, requires good loamy soil that is well-drained.
Notable SpecimensThe University of Western Ontario, Canada. The A.M. Cuddy Gardens, Strathroy, Ontario, Canada.
HabitatLow-lying ground such as flood plains.
Fruit DescriptionThe nut is enclosed by a green husk, overall larger than a golfball. Fruits in cycles, usually every second year, producing copious amounts. Can be quite messy, staining pavement and other surfaces.

Photographs